Autism Spectrum Disorder in a Child with Hunter Syndrome

Mucopolysaccharidoses (MPS) include a group of chronic and progressive lysosomal storage disorders (LSD) which are characterized by the absence or deficiency of specific lysosomal enzymes. MPS type II or Hunter syndrome (HS) is an X-linked recessive disease caused by deficiency of the lysosomal enzyme iduronate-2-sulphatase. Although the pathophysiology of Autism spectrum disorders (ASDs) is unclear, multifactorial causes are thought to play an important role in their development. Here, we report a case of HS presenting with autism-related symptoms such as restricted behaviors and lack of social interaction. To our best knowledge, this is the first report of ASD in a child with HS. In our case, the most prominent symptoms such as restricted social communicative behaviors and interest, poor eye contact, unresponsiveness to his name, repetetive behaviors, and declined enjoyment in interacting with the peers emerged were considered as autism-related which are also reported in the other types of MPS, particularly in Sanfilippo disease. Taking into account that his autistic symptoms occurred developmentally up to 3 years old, we suggested that ASD, particularly in the domains of speech, language, restricted communication, and interest, poor eye contact, and repetetive behaviors may develop concurrently in children with HS. The common genetic and biological pathways, and neural links between two disorders may undelie the development of ASD in HS cases. Clinicians should consider examining for HS, when autistic-like behaviors are observed alongside other physical or other developmental abnormalities. KEYWORDS: autism spectrum disorder, hunter syndrome, mucopolysaccharoidosis